Packaging atmosphere and method of packaging a MEMS device

Abstract

The power handling capabilities and operational lifetime of a MEMS device, e.g., a MEMS mirror, operating in a high intensity optical beam environment are enhanced by packaging the device in an packaging atmosphere having a suitably high thermal conductivity, preferably exceeding that of air. The packaging atmosphere can be selected to provide a desired level of heat loss from the MEMS device.

What is claimed is:  
     
       1. A packaging atmosphere packaging a MEMS device, the packaging atmosphere selected to have a thermal conductivity exceeding the thermal conductivity of air. 
     
     
       2. A packaging atmosphere as claimed in  claim 1 , wherein the packaging atmosphere improves the thermal stability of the device. 
     
     
       3. A packaging atmosphere as claimed in  claim 1 , wherein the MEMS device has at least one thermally dependent characteristic. 
     
     
       4. A packaging atmosphere as claimed in  claim 3 , wherein at least one said thermally dependent characteristic affects the functionality of the MEMS device. 
     
     
       5. A packaging atmosphere as claimed in  claim 4 , wherein the functionality of the MEMS device is enhanced by the packaging atmosphere. 
     
     
       6. A packaging atmosphere as claimed in  claim 5 , wherein the packaging atmosphere enables the MEMS device to handle a higher level of optical power than the level of optical power the MEMS device can handle when packaged in an atmosphere taken from the group of: air and nitrogen. 
     
     
       7. A packaging atmosphere as claimed in  claim 1 , wherein the packaging atmosphere has a thermal conductivity exceeding 0.03 Wm −1 K −1 . 
     
     
       8. A packaging atmosphere as claimed in  claim 1 , the packaging atmosphere including helium in a proportion taken from the group of: 
       at least 5% wt; 5% wt to 10% wt; 50% wt to 75% wt; more than 75% wt; 100% wt.  
     
     
       9. A packaging atmosphere as claimed in  claim 1 , wherein the thermal efficiency of the packaging atmosphere exceeds the thermal efficiency of air by a factor of 1.5. 
     
     
       10. A method of packaging a MEMS device, comprising: 
       a. surrounding a MEMS device in a packaging atmosphere which improves the thermal stability of the device; and  
       b. hermetically sealing the MEMS device within the packaging atmosphere, wherein the device is sealed in a packaging atmosphere having a thermal conductivity exceeding the thermal conductivity of air.  
     
     
       11. A method of packaging a MEMS device as claimed in  claim 10 , wherein the packaging atmosphere is selected to have composition including a proportion of helium taken from the group consisting of: 
       at least 5% wt; 5% wt to 10% wt; 50% wt to 75% wt; more than 75% wt; 100% wt.  
     
     
       12. A method of packaging a MEMS device, comprising: surrounding a MEMS device in a packaging atmosphere which improves the thermal stability of the device; and hermetically sealing the MEMS device within the packaging atmosphere, wherein the device is sealed in a packaging atmosphere having a thermal conductivity exceeding 0.03Wm −1 K −1 . 
     
     
       13. A packaged MEMS device, the MEMS device having thermally dependent characteristics affecting its functionality, the packaged MEMS device comprising: 
       a MEMS device surrounded by a packaging atmosphere and sealed within the packaging atmosphere by a packaging material, the packaging atmosphere having a thermal conductivity exceeding the thermal conductivity of air.  
     
     
       14. A packaged MEMS device as claimed in  claim 13 , wherein the packaging atmosphere extends the range over which the device is thermally stable. 
     
     
       15. A packaged MEMS device as claimed in  claim 13 , wherein the packaging atmosphere has a thermal conductivity exceeding 0.03 Wm −1 K −1 . 
     
     
       16. A packaged MEMS device as claimed in  claim 13 , wherein the packaging atmosphere is selected to have composition including a proportion of helium taken from the group of: at least 5% wt; 5% wt to 10% wt; 50% wt to 75% wt; more than 75% wt; 100% wt. 
     
     
       17. A packaged MEMS device as claimed in  claim 13 , wherein the thermal efficiency of the packaging atmosphere exceeds the thermal efficiency of air by a factor of 1.5. 
     
     
       18. A packaged MEMS device as claimed in  claim 13 , wherein the MEMS device is a MEMS mirror-type device. 
     
     
       19. A packaged MEMS device as claimed in  claim 13 , further including an atmospheric circulator. 
     
     
       20. A packaged MEMS device as claimed in  claim 19 , wherein the atmospheric circulator is a fan. 
     
     
       21. A packaged MEMS device as claimed in  claim 20  wherein the MEMS device is packaged so that the packaging atmosphere is drawn over surfaces of the MEMS device to increase the heat flow from the surfaces to the packaging atmosphere. 
     
     
       22. An optical switch having a packaged MEMS mirror device, the packaged MEMS mirror device comprising: 
       a MEMS mirror device surrounded by a packaging atmosphere and sealed within the packaging atmosphere by a packaging material, the packaging atmosphere having a thermal conductivity exceeding the thermal conductivity of air.